(Written around 2002 and posted on alt.comp.periphs.mainboard.giga-byte)

I have recently bought a GIGABYTE 7VTXE+ motherboard and
an Athlon XP 1600+. This is the first system I ever had
with a temperature high enough to make me worry. With
a room temperature of 20C, my motherboard after a couple
of hours was at 36C and my CPU at 53C. During the summer,
my room temperature will go to 35C. Will my CPU melt?
And this was in more or less idle conditions!

Fortunately, I can report that using free software-only
methods, I am now operating at motherboard:27C and
CPU:28C. This is of course, a difference big enough to
justify this text. I hope some other soul will find
this description helpful (GIGABYTE, put this in your
web site!). I'm also very pleased to report that this
works for Windows 2000, Windows 98 AND LINUX.

Simple Minds

Non-technical folk, just buy CpuIdle and make sure
you check the 'Optimize CPU/Chipset' checkbox. Your
temperature will immediately start to drop.

ACPI

Software cooling is not as simple as it used to be
(an idle thread issuing HLT commands).
Read the superb description inside VCool's help file
(http://naggelgames.de/vcool/ or http://mpet.multiservers.com/VCool.html)
To summarize, the simplest way to software (passive)
cooling, is to have a system with ACPI, and inform
the Northbridge to disconnect the bus before going
to sleep (when a HLT command is executed).

So, before
doing anything else, make sure that both your BIOS and
your OS have ACPI enabled (for 7VTXE+ owners, the BIOS
is fine).

Windows 98: Search (Google) for the string
"How to Enable ACPI Support in Windows 98". Follow
the instructions carefully, and it should work.

Windows 2000: During the installation blue screen,
press F6 (or is it F5?) and select ACPI from the
menu that appears. On an installed system, I'm not
sure, but there's a high chance that you could get
away with replacing 'ntoskrnl' with the ACPI-enabled
one. If you don't know how to do this, go to
www.osr.com's NT insider and read the article on
replacing HAL and NTOSKRNL with their checked
versions. Do the same thing in your system with the
ACPI versions.

Linux: Use one of the latest kernels (I used 2.4.18)
and select ACPI (not APM) during kernel configuration.
If it works, your next reboot will display ACPI
information during kernel startup.

OK, I have ACPI, then what?

Well, now you must tell your KT266 to "detect the HLT
command". Read the VCool help file for more details.
The summary is that inside the PCI Configuration space
of your KT266, you must set the "HLT command detect" bit,
in register 0x95. In pseudocode:

Read byte 0x95 from the configuration space of
PCI device 1106:3099 (KT266)
Set bit 1 (2nd from the right) to 1
Write the new value to the same register in the
configuration space

Windows:

Well, Windows Users, it's time to download WPCREDIT.
Search it in google, it will show up everywhere.
After installing and running it, you select device
1106:3099 (that is, your KT266) and modify register
0x95. My system had a default value of 0x18, i.e.
00011000. I changed it to 0x1A, i.e. 00011010,
and presto, the temperature started to drop.
When you verify that it works, download WPCRSET to
make the change automatically when the system
boots up.

Linux:

You 're in luck. I did all the hard work for you :‑)
(actually Martin Peters did, I just climbed on his
shoulders). Copy the following src, compile it with gcc,
and run it as root. You can use lm_sensors to
see your temperature drop in leaps. In case you don't
know it, GA 7VTXE+ has an it87 sensor, so add to your
rc.local something like this:

Caveat

Some kind souls on the newsgroups were misinterpreting this work to
be enough to forego on hardware cooling (fans, etc). Obviously, this
is a VERY BAD idea. Software cooling helps (a lot) when the CPU is idle,
but eventually you will put your CPU to work (play a game, encode a video,
etc). You need hardware cooling no matter what; what I've described just
saves energy (and extends your CPU life) for those large periods of time
during which you don't stress your CPU (e.g. when working with Word/Excel
documents, writing code with VI, etc).

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